1. Field of the Invention
This invention relates to torque-applying apparatus and in particular to controls for automatically controlling such apparatus.
2. Description of the Prior Art
In one form of torque-applying system, nut members are run onto male threaded studs or the like, to provide a tightened, set, condition therebetween. In certain applications, a number of such nut setting tools are operated concurrently to effect a setting of a plurality of nuts for improved speed and efficiency in manufacture of machinery and the like. To prevent overtightening of the nuts, control devices have been incorporated to anticipate the fully tightened condition and thereby discontinue application of torque in anticipate of the final condition which is reached by the inertia of the system. Such anticipatory circuits have the disadvantage of relative inaccuracy in the elements of the torque-applying system which may include solenoid valves having variable time delay characteristics and the like. One example of a prior art torque control system is shown in U.S. Pat. No. 3,596,718 of Charles Dennis Fish et al.